Turning Today's Zx-4 Into Tomorrow's Zx-6

Turning Today's ZX-4 Into Tomorrow's ZX-6

ROUNDUP

KAWASAKI’S ORIGINAL NINJA 600 fired the first shot in the 600cc sportbike wars back in 1985. The class quickly became one of the most hotly contested in all of motorcycling, as each of the manufacturers tried to outdo each other. This year’s big news was Yamaha’s blockbuster FZR600; but if what’s happening in Japan is any indication, that particular Yamaha may already be well on its way to obsolescence. That’s because Kawasaki looks about ready to bump up the 600-class performance ante yet another notch.

Current rumors suggest that a new, sportier Ninja 600—which will probably be called a ZX-6 in keeping with the company’s current ZX7/ZX-10 nomenclature for all-out performance models—is just around the corner. And because history shows that the 400-class sportbikes sold in the Japanese home market today evolve into the 600s sold here tomorrow, the new 400cc ZX-4 that has just been introduced in Japan gives a pretty good idea of what the upcoming 600 should be like.

The ZX-4 ranks right up there with the Honda RC30 as one of the more exotic production motorcycles ever built.

For one thing, it is the first mass-produced streetbike ever to come with an upside-down front fork as standard equipment. Upsidedown forks have been standard on serious dirt bikes for several years, but for pavement machinery, this technology has been available only on works GP roadrace bikes.

In addition, the ZX-4’s all-new aluminum “E-box” frame helps to keep weight oflf the machine—Kawasaki claims it only weighs 350 pounds—and uses the engine as a stressed member. The dohc, liquidcooled inline-Four has a 14,500-rpm redline and puts out a claimed 59 horsepower. That figure is undoubtedly a little low, however; Japanese law limits the power output of 400cc motorcycles to 59 horses, so the manufacturers regularly claim that figure even if the machines actually exceed the legal limit.

One area where the ZX-4 does exceed the limits is its price, $5912. Currently, all of the exotic 400s, machines like Honda’s NC30, Suzuki’s new GSX-R400 and Yamaha’s heavily revised FZR400, carry price tags that are nudging $6000. Which means, then, that as a 600, the ZX-6 will certainly top the six-grand mark if it retains the ZX4’s high-tech front suspension and liberal use of exotic alloys.

Such high prices for 600-class motorcycles can be somewhat justified by the quality of machinery you get these days. And remember that although the original Ninja sold for $3299, which was considered pricey at the time, the bike was a hot seller anyway because it was regarded as the ultimate middleweight sport machine of its day. So, if the ZX-4 indeed does make it to the U.S. as a 600, riders will have to pay dearly for the privilege of owning one. But they’ll at least have the satisfaction of owning what should be the ultimate 600cc sportbike.